On Oct 19, 18:10, Ian Primus wrote:
>
> I have a very large pile of 27cx321
> chips, made by a company called ICT, but I have been unable to
program
> them, since my programmer doesn't have the codes for them in the
> manual, and they don't work at the normal 2732 setting.
No, they don't, and if you try it, you may destroy them. They're
high-speed (usually 35ns, but the suffix -35, -40, or -45 gives the
actual number) 4k x 8 UV-erasable EPROMs, and to get the speed they use
a different cell construction and a different programming technique.
The bits in an erased device are "undefined" and whether you want a
'1' or a '0' you have to program the actual value. Pinout is pretty
much the same as a 2732 except that pin 20 is /CS1 instead of /OE, and
pin 18 is CS2 (active high) instead of /CE.
My ICT data book doesn't give the programming algorithm, which is
obviously proprietary. It just says contact ICT or use a DATA I/O
Model 29B with Unipak 2 or 2B firmware version V15.
Oh, and like every other EPROM manufacturer I know, ICT say that
exposing it to UV for longer than necessary will affect reliability,
shorten the life, or in extreme cases, destroy the device, so don't
expose them to a UV eraser (standard 12mW/sq.cm) for more than 20
minutes. Overnight is a bad idea!
--
Pete Peter Turnbull
Network Manager
University of York
Received on Sun Oct 19 2003 - 18:21:42 BST